The invention relates to a discharge device for manually producing a volume flow by a discharge stroke, having a medium reservoir for at least one medium, a discharge opening, a pumping device and a working area associated with the pumping device, which working area in an inoperative position is provided by means of a locking device with a detachable, positive connection to a holding area.
Numerous different designs of such discharge devices are known from the prior art. A discharge of at least one medium, particularly a pulverized solid, a liquid with an aqueous to viscous consistency or a gas is of great significance in many cosmetic and pharmaceutical sectors. For this purpose at least one medium is stored in a medium reservoir of the discharge device and can be fed by means of a manually functioning pumping device through a discharge opening into the environment. The pumping device pressurizes the medium in the medium reservoir and thereby brings about the discharge of the medium through the discharge opening. The discharge opening is matched to the viscosity and area of application of the medium to be discharged. Particularly in the case of a medium with a limited particle size, aqueous consistency and low viscosity frequently an atomization in the ambient air is sought by using a nozzle-shaped discharge opening. For a highly viscous medium on the other hand more particularly a cylindrical or conical discharge opening is preferred.
For the discharge of the medium a working area is provided, which in an inoperative position is provided by means of a locking device with a detachable, positive connection to a holding area, the positive connection consequently preventing an undesired operation of the pumping device. In order to bring about the discharge of the medium, the user exerts an operating force on the discharge device, which leads to a relative movement between the holding area and the working area. However, this relative movement only becomes possible when the operating force exerted by the user on the discharge device exceeds a control force determined by the positive connection between the working area and the holding area. This releases the positive connection between the working area and the holding area. Subsequently the desired pressure build-up in the medium reservoir of the discharge device is brought about.
Discharge devices designed for a small number of pump strokes, particularly for one or two pump strokes, frequently have a sealed medium reservoir. For this purpose the pumping device is designed in such a way that the medium to be discharged is only fed out of the medium reservoir sealed up to this time directly during the performance of the pump stroke. The pumping device opens during said first pump stroke the seal of the medium reservoir and places the latter under pressure. Discharge devices designed for a small number of pump strokes are more particularly used for the administration of inoculating agents and/or other highly active medicaments. Since then only a one or two times operation of the pumping device is required and for hygienic reasons the discharge device must subsequently be disposed of, great interest is attached to a particularly inexpensive, but reliable discharge device.
When using such discharge devices for inoculating agents, which are particularly intended for use during epidemics or catastrophes and must therefore be storable over a long time period, account must be taken of ageing effects. Ageing not only occurs with respect to the medium stored in the discharge device, but also with respect to the discharge device per se.
Discharge devices are in particular made from plastics material where, even in the case of optimum storage conditions, over a long period of time a change occurs to the material characteristics such as the material density, material volume, modulus of elasticity and notched bar impact strength. As a result of such an ageing of plastics material there can be a change to the control forces or a failure of the discharge device in use, so that doubts are cast on the application of the stored medium.